1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* The high resolution timer API provides access to the hardware timer
18 * running at around 1.1MHz. The amount this changes in a time slice is
19 * varies randomly due to system events, hardware interrupts etc
20 */
21static UCHAR randbyte_hrtimer()
22{
23    QWORD t1, t2;
24    UCHAR byte;
25
26    DosTmrQueryTime(&t1);
27    DosSleep(5);
28    DosTmrQueryTime(&t2);
29
30    byte = (t2.ulLo - t1.ulLo) & 0xFF;
31    byte ^= (t2.ulLo - t1.ulLo) >> 8;
32    return byte;
33}
34
35
36
37/* A bunch of system information like memory & process stats.
38 * Not highly random but every bit helps....
39 */
40static UCHAR randbyte_sysinfo()
41{
42    UCHAR byte = 0;
43    UCHAR SysVars[100];
44    int b;
45
46    DosQuerySysInfo(1, QSV_FOREGROUND_PROCESS, SysVars, sizeof(SysVars));
47
48    for (b = 0; b < 100; b++) {
49        byte ^= SysVars[b];
50    }
51
52    return byte;
53}
54
55
56
57/* Similar in concept to randbyte_hrtimer() but accesses the CPU's internal
58 * counters which run at the CPU's MHz speed. We get separate
59 * idle / busy / interrupt cycle counts which should provide very good
60 * randomness due to interference of hardware events.
61 * This only works on newer CPUs (at least PPro or K6) and newer OS/2 versions
62 * which is why it's run-time linked.
63 */
64
65static APIRET APIENTRY(*DosPerfSysCall) (ULONG ulCommand, ULONG ulParm1,
66                                         ULONG ulParm2, ULONG ulParm3) = NULL;
67static HMODULE hDoscalls = 0;
68#define   CMD_KI_RDCNT    (0x63)
69
70typedef struct _CPUUTIL {
71    ULONG ulTimeLow;            /* Low 32 bits of time stamp      */
72    ULONG ulTimeHigh;           /* High 32 bits of time stamp     */
73    ULONG ulIdleLow;            /* Low 32 bits of idle time       */
74    ULONG ulIdleHigh;           /* High 32 bits of idle time      */
75    ULONG ulBusyLow;            /* Low 32 bits of busy time       */
76    ULONG ulBusyHigh;           /* High 32 bits of busy time      */
77    ULONG ulIntrLow;            /* Low 32 bits of interrupt time  */
78    ULONG ulIntrHigh;           /* High 32 bits of interrupt time */
79} CPUUTIL;
80
81
82static UCHAR randbyte_perf()
83{
84    UCHAR byte = 0;
85    CPUUTIL util;
86    int c;
87
88    if (hDoscalls == 0) {
89        char failed_module[20];
90        ULONG rc;
91
92        rc = DosLoadModule(failed_module, sizeof(failed_module), "DOSCALLS",
93                           &hDoscalls);
94
95        if (rc == 0) {
96            rc = DosQueryProcAddr(hDoscalls, 976, NULL, (PFN *)&DosPerfSysCall);
97
98            if (rc) {
99                DosPerfSysCall = NULL;
100            }
101        }
102    }
103
104    if (DosPerfSysCall) {
105        if (DosPerfSysCall(CMD_KI_RDCNT, (ULONG)&util, 0, 0) == 0) {
106            for (c = 0; c < sizeof(util); c++) {
107                byte ^= ((UCHAR *)&util)[c];
108            }
109        }
110        else {
111            DosPerfSysCall = NULL;
112        }
113    }
114
115    return byte;
116}
117
118
119
120static UCHAR randbyte()
121{
122    return randbyte_hrtimer() ^ randbyte_sysinfo() ^ randbyte_perf();
123}
124